Hamfest India 2024 in Kolkata marked the launch of the TORUN – The Only Radio U Need, a new SDR transceiver by Somnath Day – VU3FBT. TORUN is a simple yet evolving Class-E driven SSB and CW SDR transceiver, adapted from the uSDX project by PE1NNZ.
Torun can do SSB communication and, when paired with a PC, can handle digital modes such as FT8, JS8, and FT4. The transceiver offers continuous tuning across 80 meters to 10 meters bands in LSB/USB modes, with a 2400Hz bandwidth, delivering up to 5W PEP SSB output. Additionally, it features a software-based full Break-In VOX for fast RX/TX switching in voice and digital operations.
Quick Specifications:
- Frequency Range : 80 Meters to 10 Meters (SSB & CW modes)
- Power Output : 5 Watts – Designed
- Modes Supported: SSB (USB/LSB), CW (decoder with full BK in), AM (Received Only), Fm (Received Only) & Digital Modes – FT8, JS8, FT4
- SSB Output Power : 5 Watts PEP
- SSB Modulation : Digital, class-E PWM-based (power-efficient and cold operation)
- TX/RX Switching : Software-based VOX for full break-in capability
- Operating Temperature: -20°C to +55°C (non ROHs Compliant), HASL with Lead
- Spurious Emission: -60dB or less
- Receiver Specifications
- Architecture: Direct-conversion SDR receiver with digital phase shift
- Sensitivity: High sensitivity on all bands (especially enhanced on 10m with DB QSD), Switchable Preamp (+18 Db).
- Selectivity: Adjustable IF DSP filters for CW/SSB with AGC and noise-reduction with three FIR filters.
- DSP
- Dynamic Range: 90-degree Hilbert phase shifting eliminates I/Q alignment, improving dynamic range
- Attenuation Control: 3 independent attenuators in the front-end for optimized dynamic range
- Audio and Signal Processing
- Audio Output: 10W low-distortion (Class A audio with bandpass filtering for clarity)
- I/Q Output: Direct I/Q available through 3.5mm audio socket for external processing (e.g., FFT)
- Digital Modes: Single-cable RS232 to USB connection enables digital modes like FSK
- Mixer: Digital mixer with a narrow 2kHz low-pass filter for excellent alias rejection
- Design: 4-layer PCB with auto-selectable low-pass filters and SWR protection
- Firmware and Upgradability: Easily upgradable via USB
- Customizable Features: Full hackable design for QRP class E MOSFETs and tunable series resonators
Key Design Highlights:
- Digital SSB Transmit Stage:
The SSB transmit stage is fully digital, powered by an ATMEGA328P. This microcontroller samples input audio and reconstructs the SSB signal by dynamically adjusting the SI5351 PLL phase via high-speed I2C and managing PA power through PWM. This innovative design enables a highly efficient Class-E driven SSB signal, eliminating the need for bulky, power-hungry linear amplifiers. The result is a compact, cool, power-efficient transceiver optimized for 5W QRP operations. - Digital Receiver Implementation:
The ATMEGA328P handles critical receiver functions, including a 90-degree phase shift, CW/SSB filtering, and audio amplification. Its Class-D amplifier simplifies the design while offering numerous benefits:
– Accurate 90-degree Hilbert phase shifting eliminates I/Q alignment issues.
– Adjustable IF DSP filters for CW and SSB.
– Built-in AGC, noise-reduction DSP, and three analog front-end attenuators enhance dynamic range and signal handling. - Audio Performance
Class-D audio, initially prone to distortion, is now upgraded to Class-A with an integrated audio bandpass filter. This enhancement ensures crisp, clear voice transmission with up to 10W of low-distortion audio power. - Improved Sensitivity and Connectivity
– Incorporates a Tyloe Quadrature Mixer with double-balanced quadrature mixing for enhanced sensitivity, especially on 10m.
– A single USB cable supports digital modes with RS232 to USB conversion, simplifying connectivity. It brings down the hassles of connecting multiple cables to a computer. Just plug it in to a computer and start digital
– I/Q output via a 3.5mm audio socket enables direct sound card interfacing for full-featured FFT and CAT control. - User-Friendly Features
– Regular firmware updates are accessible via the USB port.
– Careful component layout minimizes internal noise, ensuring optimal performance in the final version.
The TORUN is a compact, efficient, and versatile transceiver designed for modern amateur radio enthusiasts, delivering exceptional performance across voice and digital modes.
Pre-booking is currently closed but will reopen soon for the Global Amateur Radio Community.
Somanath Dey -VU3FBT aims to optimize the supply chain for components and the production process before moving forward with final production.
All necessary details will be available soon on the upcoming website.
Source: TORUN Transceiver by VU3FBT
